When we did our egg taste test back in April, comparing chicken, quail, duck and goose, I confessed to how partial I've become to duck eggs. Ever since I tasted them at Abounding Harvest Mountain Farm in Los Gatos, Calif., in March, I've been extolling their custardy texture and flavor to anyone who will listen.

I've also discovered that while the duck egg remains underappreciated and marginal in U.S. egg production, there's a growing community of people who say they prefer ducks and their eggs over the ubiquitous chicken.

So what do ducks have going for them that chickens don't? Enthusiasts say it's a mix of charisma, a taste for pestilent insects, their mild manure and the nutritional profile and baking benefits of those glorious eggs.

As we've reported, raising chickens in the backyard — or even in the house — is a trendy hobby for urbanites and surburbanites who want, as NPR's Nancy Shute describes it, cuteness and local food wrapped up in a feathered package. The backyard chicken craze has spawned a small industry of diapers for chickens that spend time indoors, saddles to protect hens from aggressive mating roosters, and "chicken crack" snack treats. Could duck diapers and duck treats be far behind?

Probably not anytime soon. Ducks are far fewer in numbers (it's hard to tell by how much). But John Metzer of Metzer Farms in Gonzales, Calif., the largest hatchery for egg-laying ducks in the U.S., says his sales of ducks for egg (and meat) production are rising fast. "It's definitely an expanding market," Metzer tells The Salt.

Metzer sells about 35,000 ducklings bred to produce eggs a year. "But that's going to grow," he says. "Every year, we put more breeders in and it's not enough. I run out quickly, and then they're back-ordered five weeks." The majority of his clients buy just a few ducks for the backyard.

One of them is Daniel Paduano, a friend who introduced me to the duck egg at his beautiful certified organic farm in the Santa Cruz mountains in March. Paduano chose ducks over chickens to raise at his small farm in 2009, and now he's one of the duck egg's most passionate advocates.

Paduano's flock of six ducks is well-suited to his farm, where he grows citrus, avocados and other fruit. Each morning, he lets the snow-white ducks out of their coop, gives them a small bowl of pellets and then ushers them out into his fields to devour the slugs, snails and insects in the soil near his avocado trees. They also snack on string algae he pulls out of his koi ponds for them.

Paduano says the ducks' ability to forage up to 90 percent of their food is one their greatest attributes. And they help him control pests around his trees. He's also a big fan of duck manure: "It is not too hot to put right on trees, unlike chicken manure which can burn trees if not composted beforehand."

Back east, Doug Toth has a small farm in Rougemont, N.C. He raises about 150 birds of various breeds: quail, guinea, chicken, duck, turkey and goose. Toth says a backyard duck's diet of bugs and other wild critters is partly what explains the amazing flavor of the eggs.

"Store-bought, grain-fed eggs always have a pale flavor and poor yolk," he says. "When my girls are out eating bugs and grasses all day, we end up with deep orange yolks. There is simply more flavor, on every level."

Paduano also chose to raise ducks over chickens because he was impressed with what he'd heard about the eggs' nutritional profile. For him, this is especially important since it's one of the few sources of animal protein his vegetarian family of four gets.

Duck eggs typically have more fat and cholesterol and a bit more protein than chicken eggs, but they can really shine when it comes to vitamins A, B-6, B-12, calcium, niacin and iron. As Backyard Poultry notes, the exact profile depend on what they eat — but Paduano's algae duck snacks are probably worth the effort.

So why aren't duck eggs in every grocery store? According to Todd Applegate, a poultry scientist at Purdue University, one of the reasons chickens became the favored egg producer is that, by weight, they're simply more efficient at converting feed into eggs.

Chickens need about 1.6 pounds of feed to make one pound of eggs, while ducks need to eat about 2.5 pounds to produce a pound of eggs, Applegate notes.

"The chickens we've bred as egg layers can now produce over 300 eggs a year while ducks will only lay 220 eggs max," he says. Ducks, though, produce eggs longer. They go for two to three years instead of the typical chicken hen's one to two years of fertility.

Toth notes that ducks are indeed big eaters. "They eat a lot more than chickens. This is painful in the winter months when they have limited forage and blow through the bags of feed. Now that they're finding good spring forage, my feed costs are about half what they were," says Toth.

While some duck producers call their birds the most charismatic animals of their households, that's not true for everyone, nor every breed. Toth admits his ducks, most of which are Indian runners, are "dumb, spastic nutcases."

Paduano favors the white Pekin ducks, which he says are "by far the best behaved" of all the ducks he has raised. (They also won't fly away.) "Ducks are funny and cute and won't peck or scratch small children," he adds.

And yet even with more people discovering the delights of raising ducks, the eggs remain difficult for the average consumer to find. The owners of backyard ducks are mostly keeping those eggs to themselves -- for now.